In order to manufacture display units including a liquid crystal display (LCD), organic light emitting diodes (OLED), a plasma display panel (PDP), an electrophoretic display (EPD), and the like, an optical film having an optical characteristic is used.
In general, the optical film has a structure in which a polarization film having the optical characteristic and a protective film protecting the polarization film are stacked. In order to manufacture the optical film, the polarization film and the protective film may be pressed while both the polarization film and the protective film having a large length may pass between a pair of rolls.
The optical film may be manufactured by a continuous process. In order to continuously manufacture the optical film, the polarization film extended by connecting the end of the polarization film and the end of another polarization film may be used for manufacturing the optical film and the protective film extended by connecting the end of the protective film and the end of another protective film may be used for manufacturing the optical film. The ends of the polarization film may be connected or the ends of the protective film may be connected by using a known bonding means such as an adhesive tape, etc.
However, when the optical film is manufactured by using the polarization film or the protective film connected by using the adhesive tape, the polarization film and the protective film cannot be completely pressed by a part connected by the adhesive tape, and as a result, the bubbles are generated in the manufactured optical film. The bubbles generated in the optical film reduce the optical characteristic of the optical film and the optical film having the bubbles causes an error of the display unit manufactured by using the optical film.